U.S. patent application number 10/607192 was filed with the patent office on 2004-01-15 for apparatus and method for correcting crt focusing.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Hwang, Gyu-Hwa, Lee, Suk-Sun, Lim, Nam-Gyu, Min, Jong-Sul, Ryu, Il-Hyeon.
Application Number | 20040008289 10/607192 |
Document ID | / |
Family ID | 29728794 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040008289 |
Kind Code |
A1 |
Hwang, Gyu-Hwa ; et
al. |
January 15, 2004 |
Apparatus and method for correcting CRT focusing
Abstract
Provided are an apparatus and method for controlling CRT
focusing in a television, and more particularly, an apparatus and
method for separately controlling focusing of R, G, and B cathode
ray tubes in a television using a triple tube type optical system
based on a digital method. The apparatus includes a memory, a
controller, and an R/G/B focusing correction signal generator. The
memory stores focusing correction data of R, G, and B cathode ray
tubes for a position of a screen. The controller reads and outputs
the focusing correction data of the R, G, and B cathode ray tubes
from the memory for the position of the screen, based on horizontal
and vertical synchronization signals. The R/G/B focusing correction
signal generator calculates the focusing correction data of the R,
G, and B cathode ray tubes read from the memory and generates R, G,
and B analog focusing correction signals that will be applied to R,
G, and B coils.
Inventors: |
Hwang, Gyu-Hwa;
(Hwaseong-si, KR) ; Lee, Suk-Sun; (Anyang-si,
KR) ; Min, Jong-Sul; (Hwaseong-si, KR) ; Ryu,
Il-Hyeon; (Suwon-si, KR) ; Lim, Nam-Gyu;
(Suwon-si, KR) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS, PLLC
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037-3202
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
|
Family ID: |
29728794 |
Appl. No.: |
10/607192 |
Filed: |
June 27, 2003 |
Current U.S.
Class: |
348/745 ;
348/747; 348/E9.025 |
Current CPC
Class: |
H04N 9/31 20130101 |
Class at
Publication: |
348/745 ;
348/747 |
International
Class: |
H04N 003/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2002 |
KR |
2002-40673 |
Claims
What is claimed is:
1. An apparatus for correcting CRT focusing in an image processing
system having a triple tube type optical system, the apparatus
comprising: a memory that stores focusing correction data of R, G,
and B cathode ray tubes for a position of a screen; a controller
that reads and outputs the focusing correction data of the R, G,
and B cathode ray tubes from the memory for the position of the
screen based on horizontal and vertical synchronization signals;
and an R/G/B focusing correction signal generator that calculates
the focusing correction data of the R, G, and B cathode ray tubes
read from the memory and generates R, G, and B analog focusing
correction signals that will be applied to R, G, and B coils.
2. The apparatus of claim 1, wherein the focusing correction data
stored in the memory is focusing correction seed data that is
determined in a predetermined number of seed points on the
screen.
3. The apparatus of claim 1, wherein the focusing correction data
comprises focusing correction data that is synchronized with the
horizontal synchronization signal and focusing correction data that
is synchronized with the vertical synchronization signal.
4. The apparatus of claim 1, wherein the R/G/B focusing correction
signal generator comprises: an R/G/B focusing calculator that
calculates the focusing correction seed data of the R, G, and B
cathode ray tubes read from the memory according to a predetermined
interpolation calculation equation, mixes the focusing correction
data synchronized with the horizontal synchronization signal and
the focusing correction data synchronized with the vertical
synchronization signal at every position of the screen, and obtains
the focusing correction data of the R, G, and B cathode ray tubes;
a digital-to-analog converter that converts the focusing correction
data of the R, G, and B cathode ray tubes output from the R/G/B
focusing calculator to an analog signal; and an amplifier that
amplifies the converted analog focusing correction signal to a
voltage that will be applied to R, G, and B focusing coils.
5. The apparatus of claim 4, wherein the R/G/B focusing calculator
comprises: R-, G-, and B-cathode ray tube interpolation calculators
that interpolation-calculate the horizontally synchronized focusing
correction seed data and the vertically synchronized focusing
correction seed data of the R, G, and B cathode ray tubes read from
the memory; R, G, and B filters that filter noise from the
interpolation-calculated focusing correction seed data; and R, G,
and B mixers that mix and output the horizontally synchronized
focusing correction data and the vertically synchronized focusing
correction data of the R, G, and B cathode ray tubes output from
the R, G, and B filters, respectively.
6. The apparatus of claim 1, wherein the R/G/B focusing correction
signal generator comprises: an R/G/B focusing calculator that
calculates the horizontally synchronized focusing correction data
and the vertically synchronized focusing correction data of the R,
G, and B cathode ray tubes read from the memory and obtains
focusing correction data of the R, G, and B cathode ray tubes; a
digital-to-analog converter that converts the focusing correction
data of the R, G, and B cathode ray tubes output from the R/G/B
focusing calculator to an analog signal; and an amplifier that
amplifies the converted analog focusing correction signal to a
voltage that will be applied to R, G, and B focusing coils.
7. The apparatus of claim 6, wherein the R/G/B focusing calculator
comprises: R, G, and B filters that filter noise from the focusing
correction data synchronized with the horizontal synchronization
signal and the focusing correction data synchronized with the
vertical synchronization signal that is read from the memory; and
R, G, and B mixers that mix and output the horizontally
synchronized focusing correction data and the vertically
synchronized focusing correction data of the R, G, and B cathode
ray tubes output from the R, G, and B filters, respectively.
8. A method of correcting CRT focusing in an image processing
system having a triple tube type optical system, the method
comprising: (a) determining focusing correction data of R, G, and B
cathode ray tubes for a position of a screen and storing the
focusing correction data in a memory; (b) reading the focusing
correction data of the R, G, and B cathode ray tubes from the
memory for the position of the screen based on horizontal and
vertical synchronization signals; and (c) generating a parabola
focusing correction signal that will be applied to focusing coils
of the R, G, and B cathode ray tubes by applying the read focusing
correction data of the R, G, and B cathode ray tubes to a
predetermined calculation equation.
9. The method of claim 8, wherein the focusing correction data
stored in the memory is focusing correction seed data that is
determined in a predetermined number of seed points on the
screen.
10. The method of claim 8, wherein the focusing correction data
comprises focusing correction data that is synchronized with the
horizontal synchronization signal and focusing correction data that
is synchronized with the vertical synchronization signal.
11. The method of claim 8, wherein in step (c), the focusing
correction data of the R, G, and B cathode ray tubes synchronized
with the horizontal synchronization signal and the focusing
correction data of the R, G, and B cathode ray tubes synchronized
with the vertical synchronization signal are mixed, and then a
parabola focusing correction signal that will be applied to the
focusing coils of the R, G, and B cathode ray tubes is generated
based on the mixed focusing correction data.
12. The method of claim 8, wherein in step (c), the focusing
correction seed data of the R, G, and B cathode ray tubes
synchronized with the horizontal synchronization signal and the
focusing correction seed data of the R, G, and B cathode ray tubes
synchronized with the vertical synchronization signal are
interpolation-calculated, the interpolation-calculated focusing
correction data synchronized with the horizontal synchronization
signal and the interpolation-calculated focusing correction data
synchronized with the vertical synchronization signal are mixed,
and the parabola focusing correction signal that will be applied to
the focusing coils of the R, G, and B cathode ray tubes is based on
the mixed focusing correction data.
Description
BACKGROUND OF THE INVENTION
[0001] This application claims the priority of Korean Patent
Application No. 2002-40673, filed on Jul. 12, 2002, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus and method for
controlling CRT focusing of a television, and more particularly, to
an apparatus and method for correcting CRT focusing by which
focusing of R/G/B CRTs is separately controlled in a television
using a triple tube type projection optical system based on a
digital method.
[0004] 2. Description of the Related Art
[0005] A projection television or a beam projector television using
a triple tube type projection system includes cathode ray tubes
(CRTs) which display red, green, and blue color images,
respectively, and then projects the red, green, and blue color
images onto a screen. However, as shown in FIG. 1, the projection
distances and the projection angles from R, G, and B CRTs 110A,
110B, and 110C through a mirror 120 to a screen 100 are different
depending on the position of the screen 100, a phase distortion
appears on the screen 100. A CRT focusing correcting apparatus has
been developed to solve this phase distortion problem.
[0006] As shown in FIG. 3, a CRT focusing correcting apparatus
according to the prior art includes first and second integral
circuits 310 and 320, an adder 330, and an amplifier 340.
[0007] The first and second integral circuits 310 and 320 integrate
a horizontal synchronization signal H_Sync and a vertical
synchronization signal V_Sync, respectively. The mixer 330 mixes
signals output from the first and second integral circuits 310 and
320, and then generates a parabola waveform. The amplifier 340
amplifies a focusing correction signal of the Parabola waveform and
then applies the focusing correction signal to R, G, and B CRT
focusing coils so that CRT focusing is corrected.
[0008] However, as shown in FIG. 1, the projection distances and
the projection angles from the R, G, and B CRTs 110A, 110B, and
110C to the screen 100 are different depending on the positions of
the R, G, and B CRTs 110A, 110B, and 110C from the screen 100.
Thus, images output from the R, G, and B CRTs 110A, 110B, and 110C
are distorted as shown in FIGS. 2 (A)-(C).
[0009] Therefore, according to the CRT focusing correcting
apparatus according to the prior art, although the projection
distances and the projection angles from the R, G, and B CRTs 110A,
110B, and 110C to the screen 100 are different depending on the
positions of the R, G, and B CRTs 110A, 110B, and 110C from the
screen 100, focusing of the R, G, and B CRTs 110A, 110B, and 110C
is corrected by using a focusing correction signal of a single
parabola waveform. Thus, CRT focusing cannot be precisely
controlled. Also, in an analog method according to the prior art,
the parabola waveform used for focusing control varies as a time
constant value of an integral circuit. Due to this, focusing cannot
be precisely corrected at every position of a screen.
[0010] In general, CRT focusing correction is performed by
employing the above-mentioned correction by a circuit and
correction by an optical system using an optical system. In a case
where the magnitude of correction operation by the circuit is small
or inaccurate, the optical system has to precisely correct
focusing. Thus, an optical system of a projection television
according to the prior art requires a larger number of lenses to
compensate for the insufficient correction of CRT focusing by the
circuit. Also, since each of the lenses has to have a precise
curvature, the optical system is complicated and costs for
components thereof increases.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present invention provides an apparatus and
method for correcting CRT focusing by which a triple tube type
optical system can be simplified by separately controlling focusing
of R, G, and B CRTs in a television using the triple tube type
optical system based on a digital method.
[0012] According to an aspect of the present invention, there is
provided an apparatus for correcting CRT focusing in an image
processing system having a triple tube type optical system. The
apparatus includes a memory, a controller, and a R/G/B focusing
correction signal generator. The memory stores focusing correction
data of R, G, and B cathode ray tubes for position of a screen. The
controller reads and outputs the focusing correction data of the R,
G, and B cathode ray tubes from the memory for position of the
screen based on horizontal and vertical synchronization signals.
The R/G/B focusing correction signal generator calculates the
focusing correction data of the R, G, and B cathode ray tubes read
from the memory and generates R, G, and B analog focusing
correction signals that will be applied to R, G, and B coils.
[0013] According to another aspect of the present invention, there
is provided a method of correcting CRT focusing in an image
processing system having a triple tube type optical system.
Focusing correction data of R, G, and B cathode ray tubes are
determined for position of a screen and the focusing correction
data is stored in a memory. The focusing correction data of the R,
G, and B cathode ray tubes is read from the memory for position of
the screen based on horizontal and vertical synchronization
signals. A parabola focusing correction signal that will be applied
to focusing coils of the R, G, and B cathode ray tubes is generated
by applying the read focusing correction data of the R, G, and B
cathode ray tubes to a predetermined calculation equation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above features and advantages of the present invention
will become more apparent by describing in detail exemplary
embodiments thereof with reference to the attached drawings in
which:
[0015] FIG. 1 is a view illustrating CRTs and a screen of a general
projection television;
[0016] FIG. 2 is a view illustrating the states of pictures
projected onto a screen by R, G, and B CRTs shown in FIG. 1;
[0017] FIG. 3 is a view of a CRT focusing correcting apparatus
according to the prior art;
[0018] FIG. 4 is a block diagram of a projection television using a
CRT focusing correcting apparatus according to the present
invention;
[0019] FIG. 5 is a detailed circuit diagram of an R/G/B focusing
correcting signal generator shown in FIG. 4;
[0020] FIG. 6A is a view of an optical system according to the
present invention; and
[0021] FIG. 6B is a view of an optical system according to the
prior art.
DETAILED DESCRIPTION OF THE INVENTION
[0022] As shown in FIG. 4, a projection television using a CRT
focusing correcting apparatus according to the present invention
includes an antenna 401, a tuner 402, a video/audio signal
detecting circuit 403, an audio signal processor 404. a speaker
405, a video signal processor 406, R, G, B CRTs 407, 408, and 409,
a controller 410, a memory 411, a synchronous deflection unit 412,
an R/G/B focusing correction signal generator 413, and a key
inputting unit 414.
[0023] The R, G, B CRTs 407, 408, and 409 have focusing coils 407A,
408A, and 409A and deflection coils 407B, 408B, and 409B,
respectively.
[0024] The basic operation of the projection television will now be
described.
[0025] If the projection television is turned on using a key button
of the key inputting unit 414, and then a channel to be viewed is
selected, the controller 410 generates a channel control signal
used for tuning the selected channel. The tuner 402 selects only a
broadcasting signal of a channel selected by a user from the
broadcasting signals received via the antenna 401 and outputs the
selected broadcasting signal, using the channel control signal.
Then, the video/audio signal detecting circuit 403 detects an audio
signal and a video signal from the broadcasting signal input from
the tuner 402 and outputs the audio signal and the video signal to
the audio signal processor 404 and the video signal processor 406,
respectively. The audio signal processor 404 removes noise from the
audio signal and compensates for frequency characteristics of the
audio signal and then outputs the audio signal to the speaker 405.
The video signal processor 406 removes noise from the video signal
and compensates for a gamma value of the video signal, converts the
video signal to an R/G/B signal, and outputs the R/G/B signal to
the R, G, and B CRTs 407, 408, and 409. Electronic beams output
from the R, G, and B CRTs 407, 408, and 409 are deflected by a
deflection voltage generated by the synchronous deflection unit 412
and then projected onto a screen (not shown). Here, a focusing
correction signal generated by the R/G/B focusing correction signal
generator 413 is applied to R, G, and B focusing coils 407A, 408A,
and 409A to correct focusing of the R, G, and B CRTs 407, 408, and
409.
[0026] The operation for correcting CRT focusing according to the
present invention will be described in detail.
[0027] First, the memory 411 stores focusing correction data of the
R, G, and B CRTs 407, 408, and 409 for each position of the screen.
The focusing correction data includes focusing correction data
synchronized with a horizontal synchronization signal and focusing
correction data synchronized with a vertical synchronization
signal.
[0028] The memory 411 may store focusing correction data
corresponding to all pixel positions of the screen. However, the
memory 411 stores only focusing correction data in a specific seed
point and calculates focusing correction data in all points of the
screen using the focusing data in the seed point, so that capacity
of the memory 411 can be efficiently reduced. In an embodiment of
the present invention, a technique for correcting CRT focusing
using correction data in a seed point is used.
[0029] The controller 410 receives a horizontal synchronization
signal H_Sync and a vertical synchronization signal V_Sync output
from the video signal processor 406, reads from the memory 411
focusing correction data of each of the R, G, and B CRTs 407, 408,
and 409 that is synchronized with the horizontal signal H_Sync at
every position of the screen and focusing correction data of the R,
G, and B CRTs 407, 408, and 409 that is synchronized with the
vertical signal V_Sync at every position of the screen, and outputs
the read focusing correction data to the R/G/B correction signal
generator 413.
[0030] The operation of the R/G/B focusing correction signal
generator 413 will be described with reference to FIG. 5. Referring
to FIG. 5, the R/G/B focusing correction signal generator 413
includes R-, G-, and B-CRT focusing interpolation calculators 501,
502 and 503, first, second, and third filters 504, 505, and 506,
adders 507, 508, and 509, first, second, and third
digital-to-analog converters (DACs) 510, 511, and 512, and first,
second, and third amplifiers 513, 514, and 515.
[0031] A horizontal synchronization signal H_Sync and a vertical
synchronization signal V_Sync are applied to the R-, G-, and B-CRT
focusing interpolation calculators 501, 502, and 503. Focusing
correction seed data Data_Rctl, Data_Gctl, and Data_Bctl, which is
read from the memory 411 by the controller 410 and synchronized
with the horizontal synchronization signal H_Sync and the vertical
synchronization signal V_Sync, is input to the R-, G-, and B-CRT
interpolation calculators 501, 502, and 503.
[0032] The R-, G-, and B-CRT focusing interpolation calculators
501, 502, and 503 calculate the input focusing correction seed data
Data_Rctl, Data_Gctl, and Data_Bctl according to a predetermined
interpolation calculation equation and obtain horizontavvertical
focusing correction data in all positions of the screen. The
predetermined interpolation calculation equation may be an average
interpolation calculation equation.
[0033] In an event that the memory 411 stores focusing correction
data in all pixels of the screen, the R-, G-, and B-CRT focusing
interpolation calculators 501, 502, and 503 are removed, and then
the horizontal/vertical focusing correction data synchronized with
the horizontal synchronization signal H_Sync and the vertical
synchronization signal V_Sync is directly input to the first,
second, and third filters 504, 505, and 506.
[0034] Then, the first, second, and third filters 504, 505, and 506
filter noise from the focusing correction data synchronized with
the horizontal synchronization signal H_Sync and the vertical
synchronization signal V_Sync, respectively.
[0035] The mixers 507, 508, and 509 mix the horizontal focusing
correction data and the vertical focusing data output from the
first, second, and third filters 504, 505, and 506,
respectively.
[0036] The first, second, and third DACs 510, 511, and 512 convert
the mixed focusing correction data of the mixers 507, 508, and 509
to an analog signal. The first, second, and third amplifiers 513,
514, and 515 amplify the analog signal and then generate R, G, and
B dynamic focusing correction signals R_D/F, G_D/F, and B_D/F that
will be applied to the R, G, and B focusing coils 407A, 408A, and
409A.
[0037] In the above-described circuit diagram, focusing of R, G,
and B CRTs can be separately corrected in a television using a
triple tube type projection system based on a digital method.
[0038] A method of correcting CRT focusing according to the present
invention will be described.
[0039] First, a first process of determining focusing correction
data of R, G, and B CRTs in each position of a screen and storing
the focusing correction data in a memory is performed.
[0040] By accessing a memory designed according to the first
process, a second process of reading focusing correction data of
the R, G, and B CRTs in each position of the screen based on
horizontal and vertical synchronization signals is performed.
[0041] A third process of interpolation-calculating the focusing
correction data of the R, G, and B CRTs and mixing the focusing
correction data synchronized with the horizontal synchronization
signal and the focusing correction data synchronized with the
vertical synchronization signal is performed.
[0042] A fourth process of converting the mixed focusing correction
data to an analog signal and generating a parabola focusing
correction signal that will be applied to focusing coils of the R,
G, and B CRTs is carried out.
[0043] Focusing of R, G, and B CRTs can be separately controlled
using the first, second, third, and fourth processes according to a
digital method. If a memory is designed to store focusing
correction data in all pixels of a screen, the interpolation
calculation in the third process is omitted.
[0044] By separately controlling focusing of R, G, and B CRTs
according to a digital method, the configuration of lenses of an
optical system can be remarkably simplified.
[0045] In other words, as shown in FIG. 6 (B), a conventional
optical system of a projection television, which uses a focusing
controlling apparatus for integrally controlling focusing of R, G,
and B CRTs according to a digital method, requires at least five
lenses for correcting chromatic aberration including a power lens
L3. Each of the lenses has to be manufactured at a high
precision.
[0046] In contrast, by precisely correcting CRT focusing using the
apparatus according to the present invention, the curvature shape
of a lens can be simplified by alleviating the correction degree of
focusing in an optical system. Also, efficiency for correcting
focusing can be improved by using only three lenses including the
power lens L3 to compensate for chromatic aberration, compared with
the prior art. Thus, in the optical system of a projection
television according to the present invention, the number of lenses
can be reduced compared to the prior art.
[0047] As described above, by separately correcting focusing of R,
G, and B CRTs according to the digital method according to the
present invention, focusing can be precisely corrected at every
position of a screen. Also, the number of lenses constituting an
optical system can be reduced compared with the prior art and the
curvature shape of the lenses can be simplified, thereby allowing
easy manufacturing of the lenses.
[0048] The present invention can be realized as a method, an
apparatus, a system, and so forth. When the present invention is
executed as software, the components of the present invention are
code segments, which carry out necessary operations. Programs or
code segments may be stored in a processor-readable medium or may
be transmitted from a transmission medium or a communication
network by a computer data signal combined with a carrier wave. The
processor-readable medium includes any media, which can store or
transmit information. The process-readable medium includes an
electronic circuit, a semiconductor memory device, a ROM, a flash
memory, a E.sup.2PROM, a floppy disc, an optical disc, a hard disc,
an optical fiber medium, a radio frequency (RF) network, and the
like. The computer data signal includes any signals, which can be
transmitted over the transmission medium, such as an electronic
network channel, an optical fiber, air, an electronic system, the
RF network, or the like.
[0049] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *